CHEX-MATE: Joint fit of the universal pressure profile and galaxy cluster masses

¹ IRAP, CNRS, Université de Toulouse, CNES, UT3-UPS, (Toulouse), France
² Université Paris-Saclay, Université Paris Cité, CEA, CNRS, AIM, 91191, Gif-sur-Yvette, France
³ Université Grenoble Alpes, CNRS, LPSC-IN2P3, 53, avenue des Martyrs, 38000 Grenoble, France
⁴ Université Paris-Saclay, CNRS, Institut d’Astrophysique Spatiale, 91405, Orsay, France
⁵ INAF, Istituto di Astrofisica Spaziale e Fisica Cosmica di Milano, via A. Corti 12, 20133 Milano, Italy
⁶ Dipartimento di Fisica, Università degli studi di Roma Tor Vergata, Via della Ricerca Scientifica 1, I-00133 Roma, Italy
⁷ INFN, Sezione di Roma ‘Tor Vergata’, Via della Ricerca Scientifica, 1, 00133, Roma, Italy
⁸ Dipartimento di Fisica, Sapienza Università di Roma, Piazzale Aldo Moro 5, I-00185 Rome, Italy
⁹ Michigan State University (MSU) - Dept of Physics and Astronomy, 567 Wilson Road, East Lansing, Michigan, 48824, USA
¹⁰ Department of Astronomy, University of Geneva, Ch. d’Ecogia 16, CH-1290 Versoix, Switzerland
¹¹ INAF - Osservatorio di Astrofisica e Scienza dello Spazio di Bologna, via Piero Gobetti 93/3, I-40129 Bologna, Italy
¹² INFN, Sezione di Bologna, viale Berti Pichat 6/2, I-40127 Bologna, Italy
¹³ Department of Physics, Informatics and Mathematics, University of Modena and Reggio Emilia, 41125 Modena, Italy
¹⁴ Dipartimento di Fisica e Astronomia (DIFA), Alma Mater Studiorum - Università di Bologna, via Gobetti 93/2, 40129 Bologna, Italy
¹⁵ Istituto Nazionale di Astrofisica – Istituto di Radioastronomia (IRA), via Gobetti 101, 40129 Bologna, Italy
¹⁶ IJCLab, Université Paris-Saclay, CNRS/IN2P3, IJCLab, 91405 Orsay, France
¹⁷ Jodrell Bank Centre for Astrophysics, Department of Physics and Astronomy, The University of Manchester, Manchester M13 9PL, UK
¹⁸ Department of Physics, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehakro, Yuseong-gu, Daejeon 34141, Republic of Korea
¹⁹ Center for Astrophysics | Harvard & Smithsonian, 60 Garden Street, Cambridge, MA 02138, USA
²⁰ HH Wills Physics Laboratory, University of Bristol, Bristol, UK
²¹ IRFU, CEA, Université Paris-Saclay, 91191, Gif-sur-Yvette, France
²² INFN-Sezione di Genova, Via Dodecaneso 33, 16146, Genova, Italy
²³ INAF, Osservatorio Astronomico di Trieste, via Tiepolo 11, I-34131, Trieste, Italy
²⁴ IFPU, Institute for Fundamental Physics of the Universe, Via Beirut 2, 34014 Trieste, Italy
²⁵ >Department of Physics; University of Michigan, Ann Arbor, MI 48109, USA
²⁶ California Institute of Technology, 1200 East California Boulevard, Pasadena, California, USA

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Published online: 20 February 2026

Abstract

Within the self-similar framework of structure formation, the thermal pressure of the hot intra-cluster medium follows a universal distribution that is independent of the cluster mass scale. Once normalised to the proper mass and redshift dependencies, this pressure distribution becomes common to all clusters. Reconstructing such a universal pressure profile requires individual estimates of each cluster’s mass. In this work, we present a methodology to simultaneously fit the universal pressure profile alongside the masses of individual clusters in a sample, while properly accounting for correlations between the profile’s shape, its amplitude, and cluster masses. We apply this method to a sub-sample of clusters from the CHEX-MATE project and demonstrate the strong impact that the assumed pressure profile has on the measured signal. This effect propagates into the thermal Sunyaev-Zel’dovich (tSZ) power spectrum and, in turn, influences the determination of cosmological parameters.